The aid group said it would create an independent commission which will have the power to access records and interview staff in a bid to stamp out abuse and impose stricter controls on employees.
“We are going to create a vetting system,” Winnie Byanyima, executive director of Oxfam International, told the BBC.
“I’m really inviting anyone who has been a victim of abuse by anyone in our organization to come forward.”
Oxfam will triple funding to more than $1 million (€800,000) to improve safeguarding, while also doubling the number of staff in this area and increasing investment in gender training.
The new plan comes a week after revelations that Oxfam staff used prostitutes while working in Haiti following a devastating 2010 earthquake and a wave of subsequent allegations of sexual misconduct.
The charity’s deputy chief executive Penny Lawrence has resigned and three Oxfam global ambassadors including South Africa’s Archbishop Desmond Tutu have quit their roles as a result of the scandal.
“What happened in Haiti and afterwards is a stain on Oxfam that will shame us for years, and rightly so,” Byanyima said, adding: “From the bottom of my heart I am asking for forgiveness.”
Oxfam fired four staff members for gross misconduct and allowed three others to resign following an internal inquiry into what happened in Haiti in 2011.
But Roland van Hauwermeiren, Oxfam’s director in Haiti at the time and one of the three who resigned from the charity, dismissed the allegations.
“I have never been into a brothel, a nightclub or a bar in that country,” the 68-year-old Belgian national said in a four-page letter published on the website of Belgian VTM News.
“There were numerous men and women who tried to get into my house with all sorts of excuses to demand money, work, or to offer sexual services. But I never gave into these advances,” he said.
Van Hauwermeiren, who has taken part in an internal enquiry at the British charity, said he told Oxfam that he had “had intimate relations some three times at (his) house.”
“This was with an honorable, mature woman, who was not an earthquake victim nor a prostitute. And I did not give her any money,” he said, adding that he was however “deeply ashamed” of the liaison.
In comments to reporters at the newspaper Het Nieuwsblad, who tracked him down in an unidentified town on the Belgian coast, Van Hauwermeiren said there were “lots of lies and exaggerations” in media reports.
“The hardest thing is that my family has rejected me,” he said.
The charity has denied covering up the Haiti affair, which has prompted a drop in donations and led the British government to threaten to cut funds to organizations which try to hide sex scandals.
The charity admitted Thursday it rehired one of those sacked in Haiti just months later and is now checking whether any complaints were subsequently made.
Gurpreet Singh worked as a consultant in Ethiopia from October to December 2011, a decision Oxfam said was “a serious error and should never have happened.”
The charity on Friday said it was also investigating allegations of sexual misconduct at a hotel in the Philippines after a destructive typhoon in 2013.
Oxfam’s regional director for Asia Lan Mercado earlier this week told the BBC she was aware of cases of sexual abuse involving staff in Bangladesh, Nepal and the Philippines between 2009 and 2013.
Oxfam has come under fire for failing to inform other aid organizations of the allegations against its staff including Van Hauwermeiren, who went on to work for French charity Action Against Hunger in Bangladesh.
“We need to make sure anyone guilty of such gross misconduct is not able to move between different organizations, exposing more vulnerable people to risk,” said Byanyima.
In response, Oxfam on Friday said it would create a global database of accredited referees to crack down on forged or unreliable references from past or current employees.